"I don't think that working class folks all just spontaneously decided that traditional trades were somehow 'beneath' them,"

Absolutely! In most instances their jobs were destroyed, especially in the mining, steel and many manufacturing industries. For that, we can blame the likes of Thatcher, McGregor, Hesseltine etc. Even the newer coalfields have now been closed and dismantled - twice a day I pass the remnant of Gascoigne Wood in the Selby coalfields, scene of the famous 'bull-run' and subsequent police brutality during the '84 conflict. Similarly, in Hull, the docks and the fishing industry have been dismantled - no wonder we have such fertile ground for the BNP's lies to take root.